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Re: Astronomy: Calculating Positions
From: Paul Hirose
Date: 2008 Apr 07, 13:47 -0700
From: Paul Hirose
Date: 2008 Apr 07, 13:47 -0700
I wrote: > > I have a free Windows positional astronomy DLL online which does these > things. There's also a C++ example which uses the DLL to compute > geocentric and topocentric positions of a star and the Moon. > http://home.earthlink.net/~s543t-24dst/sofajpl/lunardist.html There's a difference of several arc seconds between the sample run and the JPL HORIZONS online calculator. It's a time scale discrepancy. The sample run assumes values for (TT-UT1) and (UT1-UTC) which are significantly different from the actual values of date used by HORIZONS. The USNO MICA program will duplicate the sample run if you use the values of TT and the ephemeris longitude of the observer shown in the sample run output. I should change the parameters so the results match HORIZONS. -- I block messages that contain attachments or HTML. --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---
